Advanced retirement planning: Mega Backdoor Roth and more

When you’re working with high-net-worth clients, the standard retirement conversation is usually insufficient. Maxing out a 401(k) and adding a SEP or profit-sharing contribution might check the compliance box, but it often does very little to materially change a client’s tax liability.

The gap between what most high earners are doing and what is actually available under the code is significant, and that gap represents one of the clearest advisory opportunities in your practice.

For the right client profile, annual tax-advantaged contributions can reach $200,000, $300,000, or even more. The tools are not new. They are just underutilized.

The contribution gap: why standard plans are not enough

For 2026, the 401(k) elective deferral limit is $24,500. With employer profit sharing, total defined contribution plan limits increased to $72,000. That is meaningful for many clients. But for a business generating $500,000 or more in net income, a $72,000 pre-tax contribution may not significantly move the overall tax picture.

This is where the conversation shifts from “max out your 401(k)” to “what is the total retirement capacity of this business?”

When you frame it that way, you begin to see how much planning room is left on the table.

Cash balance plans: the heavy lifter

A cash balance plan is technically a defined benefit plan, but from the participant’s perspective it resembles an account balance that grows annually at a stated crediting rate. From a tax standpoint, employer contributions are fully deductible and contribution levels are driven by actuarial calculations based on age and compensation.

Cash balance plan contributions are determined by actuarial valuation based on your client’s age, compensation history, and the benefit formula the plan sponsor chooses. Because the IRS annual benefit limit for defined benefit plans (including cash balance plans) is around the mid-$200,000s for 2026, older, higher-earning participants often support very large deductible contributions in practice.

The most powerful structure layers a cash balance plan on top of a 401(k) with profit sharing. The owner first maximizes the 401(k) elective deferral and employer contribution, then adds the cash balance contribution. For a profitable 55-year-old owner, total deductible retirement contributions can exceed $300,000 in a single year.

Of course, this is not plug-and-play. Cash balance plans are subject to ERISA and require annual actuarial certification. Administrative and actuarial costs are typically in the range of a few thousand dollars annually. If the business has employees, they must generally be included, which increases the overall funding requirement. These plans work best in businesses with few employees, or where employees are younger and lower compensated.

Cash balance plans also require consistency. Before recommending one, confirm that the business has stable cash flow and can sustain required contributions.

When presented properly, this is not an abstract idea. It is a concrete savings calculation. Instead of saying, “You could contribute more,” show the client what an additional $200,000 deduction does to their federal and state tax liability this year. High earners respond to numbers.

ProTip: For the right client, a cash balance plan can become one of the most valuable planning opportunities you offer all year. The key is to quantify the opportunity clearly. Model the additional deductible contribution, estimate the federal and state tax impact, and present the strategy as a concrete planning decision rather than a general retirement idea.

The Mega Backdoor Roth

While the cash balance plan focuses on large deductible contributions, the Mega Backdoor Roth focuses on long-term tax-free growth. For high earners who are phased out of direct Roth IRA contributions, the Mega Backdoor Roth can allow significantly more money to move into Roth status each year. The structure is straightforward in concept: Make after-tax contributions to a 401(k) beyond the elective deferral limit, up to the overall annual plan cap, and then convert those after-tax amounts to Roth either inside the plan or through a rollover to a Roth IRA.

This strategy only works if the 401(k) plan document allows after-tax employee contributions, and either in-plan Roth conversions or in-service distributions of after-tax amounts. Many standard payroll-provider plans do not include these features automatically. For owner-only plans, amendments are often possible, but the plan must be reviewed carefully.

This is not a strategy you assume is available. It is one you verify.

Multi-vehicle stacking

The most advanced planning approach is not choosing between strategies; it is stacking them intentionally.

A high-earning business owner may have access to:

• 401(k) elective deferrals.
• Employer profit sharing.
• After-tax contributions for Mega Backdoor Roth conversion.
• A cash balance plan.
• An Health Savings Account for triple tax-advantaged savings.

When layered properly, total annual tax-advantaged contributions can reach several hundred thousand dollars. For the right client profile, there is no other recurring strategy in the code that produces this level of tax deferral and long-term compounding potential.

The key is not complexity for its own sake. It is alignment. The client must have the income, cash flow stability, and long-term horizon to justify the structure.

Why this is an advisory conversation

Retirement planning is one of the cleanest ways to move from compliance to advisory.

Every business owner cares about their tax bill. Every business owner cares about long-term security. When you combine those two in a midyear planning conversation, the value is visible.